1. Field of the Invention
The present invention relates to a memory element and a semiconductor device that includes the memory element.
2. Description of the Related Art
In recent years, development of a semiconductor device in which a plurality of circuits are integrated together over an insulating surface and that has a variety of functions has been progressing. In addition, development of a semiconductor device in which electromagnetic waves received by an antenna provided in the semiconductor device are converted into electrical energy and transmission and reception of data is performed using this electrical energy has been progressing. This kind of semiconductor device is referred to as a wireless chip (also referred to as an ID tag, an IC tag, an IC chip, an RF (radio frequency) tag, a wireless tag, an electronic tag, and RFID (radio frequency identification) and has already been introduced into a part of the marketplace.
Currently, many of these semiconductor devices that have been put into practical use have a circuit (also called an IC (integrated circuit) chip) formed using a semiconductor substrate of silicon or the like and have an antenna. In addition, the IC chip is formed of a memory circuit, a control circuit, and the like. In particular, by provision of a memory circuit with which a lot of data can be stored, an even more highly functional semiconductor device with an even higher added value can be provided. However, even though silicon substrates are expensive, manufacturing these semiconductor devices at low cost is demanded. This is because of an expectation that small semiconductor devices like a wireless chip will need to be semi-disposable. Given this, in recent years, development of organic devices, for example, organic thin film transistors (hereinafter also referred to as organic TFTs), organic memory devices, and the like, in which a control circuit and a memory circuit are formed over a low-cost glass substrate and, furthermore, the control circuit and memory circuit can be formed using an organic compound formed at low temperature, is actively being carried out (for an example, refer to Patent Document 1: Japanese Published Patent Application 2002-26277).